Hi All,
I have a rather technical question for some of you engineering types.
I've been trying to figure out a way to ask the following questions without
sounding naive. I'm a little afraid of the answers I'll get.
This Devin-bodied Porsche that I bought a couple of months ago is now
laying on it's side on a homemade rotisserie. I have ample opportunity to
study it's structure which is composed of a Porsche front suspension,
Porsche rear suspension and a homemade floor welded from the Porsche
toeboards back to the rear seat section. The rigidity of the tube chassis
is made up of a series of longitudinal tubes running between the original
rear seat area (near the transmission mount) to the front torsion bar
tubes. Hoops under the front cowling attach the two sides as do the front
and rear torsion bar tubes. The longitudinal tubes are triangulated. Most
of the tubes seem to be welded quite nicely. 18 or 20 guage sheetmetal is
MIG welded to the pipes which may add some additional triangulation and
stiffening.
I plan to replace the homemade floor with a proper Porsche floor which will
be stronger.
The questions:
How have you folks assessed the structural strength of your chassis?
Anybody know how to calculate how many pounds of force a given piece of
pipe can withstand? Can anyone calculate (approximately) how may pounds of
force is generated under cornering given tires, weight, speed...?
Fully loaded, this car will probably not exceed 1200lbs. Except for center
of gravity, it must be similar to a formula V (I would think) as far as
stresses on the chassis components. What are these cars made of?
I can't imagine everyone before me who has restored a non-production-car
vintage racer has the ability to assess chassis strength with all the
engineering math. I also don't think I'm going to get some professional to
come over and give it approval because he would be opening himself up to
liability problems. Not to mention he would probably have to have unique
experience with a similar chassis design, welds, potential weaking from
rust in the tubes, etc.
I keep thinking that if I had purchased this car restored and race ready, I
would assume everything under that body was just fine (because it was all
painted purdy). Do I just make my best guess and do some stress tests
under power with nobody around?
Am I making too big a deal out of this?
Clark
"Hay Bales and Asphalt"
a video featuring vintage footage
of motor racing from 1957 to 1961.
Images and description at
http://www.dnf.com
My 1953 Devin-Porsche Restoration project
http://www.dnf.com/devin-porsche.html
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